Permanent magnet steel



Patented'sept. 4,1945

2,383,969 PERMANENT. MAGNET STEEL David. R. Howerton, Riverside," 11]., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York No Drawing.

This invention relates to a permanent magnet steel, and more particularly to a permanent magnet steel alloy including among other ingredients tungsten and chromium.

It has been the practice in manufacturing certain types of magnet steels to use an alloy of iron, cobalt, and molybdenum and small amounts of carbon, manganese and silicon. Although this composition produces an alloy of suitable magnetic qualities, the alloy has a relatively low impact strength. It certain uses this feature constitutes a distinct disadvantage. v

It is the object of the present invention to provide a permanent magnet alloy having good impact strength.

A typical composition heretofore used in the manufacture of a permanent magnet steel is as follows: a

Per cent Iron 70.5 Cobalt 12.0 Molybdenum n u" 17.0 Carbon .04 Manganese .35 Silicon .10

liiaximum. V

This composition produces a steel known commercially as- Remalloy, which has excellent remanence and high coercive strength. As is well known to the art, these are very desirable tungsten and chromium has been used in amounts.

up to 25% of the charge as a source of both the chromium and the tungsten with satisfactory results. The exact proportion that may be used depends on the amount of tungsten and chromium in the scrap cobalt steel. Other ingredients of the charge are introduced in conventional manner.

Iron, cobalt, cobalt steel scrap and ferro manganese may be melted together under a lime slag. Iron ore is then added to oxidize the bath thoroughly until the. carbon content is .03% or less and then the slag is replaced; The charge is then superheated and ferro manganese and term molybdenum are added. A typical analysis of the alloy produced in thiamanner is:- 11.84%

Application December '23, 1941, Serial No. 424,126

2 Claims. (01. 75-126) cobalt, 16.08% molybdenum, 58% tungsten, .07% chromium, .03% carbon, 10% silicon, 35% manganese, and the rest iron.

. This alloy is readily hot workable and possesses rnerous melts to give an average.

"alloy bars which did not contain tungsten or chromium showed an average dropping distance, required to break the bars of 9.3 divisions on the above scale, while the dropping distance with bars containing chromium and tungsten "averaged 15.25 divisions, which is clearly a very substantial improvement.

In practice, it has been found that the essential I composition of this alloy may be varied somewhat, as follows, without substantially affecting the final product:

'tion and that many changes may be made therein .without departing from the spirit or scope of the invention.

What "is claimed is:

- 1. A permanent magnet steel comprising 11- 13% cobalt, 16-18% molybdenum, .5-1% tungsten, .05-.5% chromium, a maximum of 414% carbon and of .10% silicon, 30-50% manganese. and the rest' iron. 7 2:11 permanent magnet .steel comprising 11.84% cobalt, 16.08% molybdenum, 58% tungsten, .07% chromium. .03% carbon, .0896 silicon, .3596 manganese, and the rest iron.

nsvm a. aowra'mn. 

